An archaic or dialect word for a grinding stone, mill component, or possibly a malicious or troublemaking person.
Possibly from Old English 'grindan' (grind) with a diminutive suffix, or influenced by words like 'swindle.' The exact etymology is uncertain, but it appears in regional English dialects.
Some words just sound like trouble—'grindle' has that quality where even the sound suggests mischief or grinding away at something, which is probably why it got used both for mill parts and for annoying people.
Complete word intelligence in one call. Free tier — 50 lookups/day.